Why Apple buys a PowerPC Chip Designer?

So Apple buys PA Semi, who design processors based on the PowerPC architecture that Apple moved away from when they made the Intel switch in 2006.  Well it's certainly not a case that they want to move away from or damage their relationship with Intel.  However the move to Intel has meant that it is harder for Apple to differentiate its hardware designs from any other PC manufacturers.  Apple also invests a huge amount of effort in software that outsources processor intensive tasks out to specialised hardware (such as Core Graphics and Core Animation).  Adding power efficient specialised chips from in-house designers would be one way to provide performance in Mac computers which others would have trouble copying.  Similar competitive advantage could be extremely important in the portable wireless device market (iPhone, iPod) so I think this is a very shrewd move by the king of innovation.  It would indeed be typical of the clever strategic moves often made by the company but which rarely hit the headlines.